Insanity
by Fire Sidoni
Summary: SaiyukiHarry Potter crossover. When the Saiyuki boys are invited to Hogwarts to teach, insanity ensues! But where's Hakkai?
1. Chapter One

**Chapter 1: New DADA teachers arrive, and a secret revealed **

Dumbledore stood up, tapping his goblet to get the attention of the crowded hall. "Before we all dig in to this excellent meal, I have a few announcements to make. First years are warned that the Forbidden Forest is, as the name suggests, forbidden, and several of our older students should remember that as well," he said, twinkling sapphire eyes lighting upon the Weasley twins, Harry, Ron, and Hermione.

"The Defense Against the Dark Arts teachers have not arrived yet, but you are all in for a treat this year. Our teachers are a group of four who have come all the way from Japan, and I have been informed that two of them will be taking certain seventh year courses as well. They have asked us to begin without them, so without further ado, let the feast begin!"

Speculations were running wild about who the teachers would be this year, and what species. Suggestions varied, from banshees and werewolves, to veelas and vampires.

Harry smirked mentally. Would they be in for a surprise!

The door of the Great Hall opened slightly, letting in a small white blur that locked in on Harry. The teachers immediately jumped up, training their wands on the blur, but Harry beat them to it, jumping up and catching it, revealing it to be a small, white- dragon?

It crooned happily, as Harry cried "Hakuryuu!" Seeing the teachers' shock he added, "Don't worry, Hakuryuu is an old friend."

Uncertainly, they sat back down, but before anyone could resume eating, the doors sprung open the rest of the way, accompanied by an angry tirade.

"HAKURYUU! You dumb dragon, transforming as soon as we got here and zipping off! You couldn't have given us a ride, could you? K'so…" growled an irate blond monk, accompanied by a panting redhead and a chipper brunette boy.

"Ne, Sanzo, I'm hungry! You said you'd give me meat buns, so where are they?"

Dumbledore stood up, eyes twinkling. "It seems our DADA teachers have arrived. Genjo Sanzo, Sha Gojyo, Son Goku, and- where is Cho Hakkai?"

"Umm…" came a timid voice from the Gryffindor table. It was Harry Potter.

"Hakkai? Thank Kami! Take off that ridiculous concealment charm already and introduce me to these lovely ladies!" Gojyo proclaimed, leering at several Ravenclaw girls."

"Hakkai! I said I wouldn't forget your name and you promised you would never leave again! You broke your promise! You left waaaay before us! Now you have to buy me meat buns!" Last was Goku, who had attached himself to Harry's neck, looking very strange because Goku was taller than Harry.

"Heh. You're always hungry, baka saru."

"Oi! I'm not a monkey! Ero hentai kappa!"

"Baka Saru!"

"Hentai Kappa!"

"Shut. Up." /click/ Sanzo cocked his gun, causing the two to immediately quiet down and be faced with the disbelieving stares of the entire hall. "Hakkai. Take. It. Off. Now!"

"Hai, hai!" Harry sweatdropped, before removing his glasses and closing his eyes. A slight wind blew around him, and as the contents of the Hall watched, Harry Potter changed.

He grew taller, much taller than his previous height, until he was about Gojyo and Sanzo's height. His face narrowed, and his hair settled down against his skull before it growing longer, until half of his face was covered by his bangs. Now, only one eye was visible. His robes melted into a green and black Chinese style shirt with a sheet of white covering one shoulder. He opened his eyes, and many gasped softly at their intensity. He reached into a pocket and took out his glasses. They warped before changing into the monocle he preferred. Settling that on his nose, he turned to Gojyo and Goku who had started arguing again. "Now, now!" He said with the smile on his face, "Goku, if you're hungry, we can get you meat buns from the house elves later."

"Hakkai!" He was immediately glomped by Goku and Gojyo, and even Sanzo smiled slightly.

"Well, it seems we have known one of the teachers for a while," said Dumbledore, still rather shocked. "Students, this is Cho Hakkai, our fourth DADA teacher. Let's give them a warm welcome!"

The hall erupted into uncertain applause as Gojyo chased Goku, yelling obscenities while the latter stuffed meat buns in his mouth. Sanzo developed a tic in one eye, and Hakkai simply stood there with his normal cheery smile as he watched his teammates' antics, trying to calm them down.


	2. Chapter Two

**Chapter 2: Explanations**

The feast passed in a bit of a blur for everyone. As the students began to leave for their dorms, Hakkai began to stand up and follow the Gryffindors, then paused, uncertain.

"Ah- Professor Dumbledore? Er… where do I go? I'm… not quite a student, but…"

Dumbledore smiled faintly, the ever-present twinkle in his eye returning full-force after the surprise.

"I suppose that, as you _are_ teachers, I'll give you a choice of staying with your old House or moving into the Defense teacher's quarters."

The four looked at each other, Gojyo and Sanzo having moved closer during the conversation, and after a moment's silence, they responded at once, stating flatly, "Teacher's quarters. Separate rooms."

As soon as they entered the rooms and Dumbledore exited, bidding them all a good night, Sanzo locked the door, turned around, and glared at Hakkai.

"Start explaining. Now."

Hakkai sighed a bit, and began, lapsing into their native Japanese. "Ah… you remember that last fight we had?" The four paused a moment, thinking back on that fateful day…

_Gojyo narrowly ducked a blast of energy sent his way. "Damnit, stop stealing Hakkai's moves!" he joked, sending his shakujo through the offending demon. "They're starting to piss me off, doing that. What'd'you think, Hakkai?"_

_Hakkai smiled wryly. "There does seem to be a certain lack of creativity here," he shot off a blast of his own, "But then I suppose we're doing our part to fix that," another blast. "After all, it's rather hard for them to copy us," spin-duck-blast, "When they're dead."_

_Goku grinned madly at the thrill of the fight, killing demon after demon. "Yeah, but have you ever noticed who they end up copying? 'S'always you."_

_Gojyo smirked. "Hey, Hakkai, think they're hitting on you? You know, imitation being the sincerest form of flattery and all that crap?"_

_Hakkai twisted slightly, mock-glaring at the two. "Hey, now, don't even joke about that."_

"_Hey, now, who said I was- shit, Hakkai! **Move!**" But Gojyo's warning came a moment too late, as Hakkai was hit from behind by a strange bolt of energy._

_Time seemed to stop, as Hakkai fell slowly to his knees, his body seeming to twist and warp oddly, and began to fade away. He managed to choke out a few words, and then- was gone._

"_Hogwarts … Harry Potter… fifteen… years…" _

((A/N: I'm back! Finally! I've got some explanations planned out, at least, but I just wanted to get this out, even though it's short. Chapter one has been redone, so you may want to go back and reread that. Hopefully, there won't be such a gap before the next chapter comes out… ;

And a big thanks to all my reviewers!))


	3. Chapter Three

Disclaimer: _Saiyuki_ belongs to the great Kazuya Minekura, and _Harry Potter_ to J. K. Rowling.

**Chapter 3**

Goku was the first to speak, and for the first time that day, his face was pained, so unlike his normal, happy-go-lucky mask.

"We looked for you for so long after that, but you were gone…" he trailed off sadly.

Gojyo cut in, "And what the hell was that thing about 'fifteen years?' You had the damn monkey convinced we wouldn't see you for another fifteen years!"

Hakkai started slightly. "You mean… it hasn't been that long for you?"

Gojyo looked at him blankly, uncomprehending. "No… it hasn't even been a year since that happened. What, has it been longer for you?"

Hakkai shook his head slowly. "I… I think I'd better start at the beginning. You three may want to sit down for this." A pause, then he began.

"Understand, now, that there are still some holes in my knowledge of the matter. Why… well, you'll see why in a moment.

"That blast that hit me… to be quite blunt, it killed me. No-" he held out his hand to forestall the inevitable questions, "I'm not a ghost or anything, just wait a moment. I suppose that what I should have said was that it destroyed my body, but my… soul, I suppose, was left to wander. This," he smiled wryly, "is where things get interesting.

"At that precise moment, a young mother, desperate to save her child's life, accidentally invoked an ancient magic. I'm still a bit unclear on the details, but as she died, she summoned a- guardian, I suppose, to save her child. That 'guardian'… was me. 

"My soul was dragged to her child, and bound in his body. I sensed a tremendous burst of deadly power coming at us, and—well, the demon side came out instinctively. The last thing I remember was throwing up a chi barrier, and pouring all my strength into it.

"When I finally awoke… fifteen years had passed. I was still sealed inside the child's body, but he was completely unaware of me. That was this last summer. We had some… _interesting_ experiences over the past few months, and made a few discoveries. No, Gojyo, not like that, so please stop smirking.

"One of these was that I can take control of Harry's body. I _can_ revert to my own form, as I am now, but that takes enough energy that I won't be doing it often. What will usually happen is that I'll be using Harry's form, but my mind will be the one in control, so to speak.

"And speaking of which, I'll… see you guys later." Before the others could react, Hakkai quietly fell back into a chair, form morphing into that of Harry Potter.

Harry blinked a bit, not quite prepared for the change, then sighed.

"Damnit, Hakkai… stretching the time limit _again_?"

Sanzo raised an eyebrow. "So, do they actually teach a worthwhile language here, then?" he asked dryly. Harry just stared blankly at him, obviously not getting his point.

"You were speaking Japanese, if you didn't notice," Goku said quickly, noticing Sanzo's hand creep towards his fan.

"Oh, that? Ah… Hakkai taught me a bit… we had rather a lot of time this summer. We actually traveled a lot, for various reasons. Rather convenient, actually… _I_ may still be a legal minor, but _Hakkai_ isn't, so…" A rather devilish smile stole onto his face, "We had a bit of… _fun_." Gojyo smirked appreciatively at that.

Harry yawned, then smiled sheepishly. "Hate to break up the party, but we're still having a bit of trouble with judging how long Hakkai can stay out without problems, and he rather stretched the limit, so 'm rather drained. G'night, and don't forget, first class is tomorrow morning." He got up and headed off to bed, yawning.

One thought, though, was running through everyone's head.

_This is going to be an interesting year…_

((A/N: Wow, I got another chapter out already! Again, it's short, but they're at least getting longer.

A note: I realized as I was planning this out that Harry's and Hakkai's body-sharing and whatnot are suspiciously similar to that of _D.N.Angel_. This is entirely unintentional, but it works. (I blame my recent obsession with the previously noted anime. Watch it. Now. The VAs for the four main males are the English voices of Gojyo, Goku, Kouryuu, and Kougaiji.)

Until next time,

Fire))


	4. Chapter Four

**Chapter 4: Conflict and Confrontation**

The next morning, Harry woke to Hakkai's mental voice gently prodding him awake. _Come on, Harry. You're the one who knows his way around this damn castle, not me._

At the wry amusement lacing his guardian's voice, Harry woke just enough to form a vaguely coherent response. _Ah, f'ck off, 'kai. Y'should know th' way t' breakf'st, anyway._

Hakkai laughed. _Yes, but you need to wake up regardless. We get timetables today, and you have a class first period. We're already dressed, so you just need to wake up enough to get some of the coffee._

Harry yawned widely and took control of his body. As he slipped into the Great Hall, all noise stopped for a moment as the students stared at Harry, then began again as the whispers started.

Harry twitched slightly, then tried valiantly to ignore them, walking calmly to his habitual spot at the Gryffindor table. As soon as he sat down, he was accosted by Ron and Hermione, who began bombarding him with questions.

"What in the bloody hell-" "Barely responded to our owls-" "Never told us anything-" "Worried sick-" "Mum was about to have a cow!"

Harry winced slightly, especially at the last. "Look, I'm really sorry about that. It's just that, with a certain snake-head and followers running around trying to kill me, I didn't want it to get out before absolutely necessary. Bad enough it had to get out now, but before… well, you understand, don't you?"

Hermione looked around for a moment before hissing furtively, "You could have at least let the Order know! They could have helped you!"

Harry gave a short, bitter snort of laughter. "Think about it, Hermione – I just found out there's a person in my head who can take over my body at will. You really think they'd be okay with that, after the ministry incident? Maybe, oh, the whole 'Voldemort possessed me' thing? It was bad enough last year, when they only suspected it was possible. How do you think they'll react now?"

The next thing he knew, his cheek was stinging from the slap delivered it by Hermione. She looked horrified at what she had done just moments later, but hissed, "You couldn't have trusted _us_?"

Harry laughed dryly, no humor evident in his voice. "And what would you have done if I had? Can you honestly say you wouldn't have run off and told someone first thing?" He paused, sighed. "I suppose I can't blame you, after what happened at the Ministry, but- Hell. I wasn't thinking straight." He winced again, rubbed his still-stinging cheek, and laughed again, this time rather ruefully. "I suppose I deserved that. Look-" he lowered his voice, "Meet me in the Room of Requirement after classes let out today."

"I'll explain. I promise."

_A/N: Awp, this is short. Thing is, a) school is devouring my soul, and b) I'm having a hell of a time getting a handle on the voices and personalities of the HP characters. Of course, it doesn't help that Harry, especially, changes so much in the last few books._

_A note: this is now officially AU after OotP, and a few minor details have been changed to reflect this. Pieces of HBP may or may not get worked into the story, depending on how things work out._

_Concrit and nitpicking are welcomed, even if it's some tiny little error, and especially if it's feedback on the voices: despite being an HP canon-freak, I have no clue whether or not I'm getting them decently, so any feedback would be greatly appreciated. Thanks!_

_Fire_


End file.
